To increase their performance, internal combustion engines are often equipped with inlet air compressors, which compress combustion air for the internal combustion engine so that a greater mass flow rate can be achieved in the same cylinder capacity. The inlet air compressor can be driven by the internal combustion engine or may be mechanically coupled to an exhaust gas turbine disposed in the exhaust gas flow of the internal combustion engine. In the latter case, the compressor forms part of what may be referred to as an exhaust gas turbocharger.
In the process of controlling the internal combustion engine, the mass flow rate of inlet air may be adapted to current operating conditions. The mass flow rate can, for example, be adjusted depending on the current engine power demand by adjusting the revolution rate, or, for variable geometry turbochargers, the geometry of the compressor impeller. As such, knowledge of the current mass flow rate may be desired.
U.S. Pat. No. 6,298,718 describes systems and methods for detecting abnormal operation of a turbocharger compressor. In one example, a series of rationality tests are conducted on data obtained from a plurality of sensors including a mass air flow sensor disposed at the outlet of the turbocharger compressor. A rationality test specific to the mass air flow sensor, which along with a boost pressure sensor may be used to determine the condition of ambient air provided to an engine, may be performed to test the rationality of the mass air flow sensor.
The inventors herein have recognized an issue with the approach identified above. Mass air flow sensors can be expensive and are prone to degradation, which can lead to degraded engine operation. Moreover, such potential degradation motivates performance of the mass air flow sensor rationality test, which consumes energy and increases engine control complexity.
One approach that at least partially addresses the above issues includes a mass flow rate sensor configured to determine a mass flow rate of an inlet air compressor of an internal combustion engine, the mass flow rate sensor comprising a first signal input for a revolution rate signal of the inlet air compressor, a second signal input for an output pressure signal of the inlet air compressor, an output for a mass flow rate signal, a first characteristic field, a second characteristic field, each of the first and second characteristic fields associating a mass flow rate value with a pair of values of a revolution rate value and an output pressure value respectively received via the first and the second signal inputs, and a selection unit that comprises a first parameter input and a second parameter input, the selection unit configured to produce a selection signal depending on a pair of parameters respectively received via the first and second parameter inputs and to switch the mass flow rate value of either the first or the second characteristic field through to the output of the mass flow rate sensor depending on the selection signal.
In a more specific example, the first parameter input of the selection unit is connected to a revolution rate signal of the internal combustion engine and wherein the second parameter input of the selection unit is connected to a torque signal of the internal combustion engine.
In another example, the first and the second parameter inputs of the selection unit are respectively connected to the first and the second signal inputs of the mass flow rate sensor.
In this way, the mass flow rate of an inlet air compressor may be accurately inferred without the cost, complexity, packaging space, and potential degradability of a physical, dedicated mass flow rate sensor. Thus, the technical effect is achieved.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. Finally, the above explanation does not admit any of the information or problems were well known.